Alrighty then, I was able to get a VI job to work and create the batch of void checks. We did this by reverse engineering a manual adjustment. I entered a check reversal and then created a VI export to dump all values in the AP_ManualCheckDetail, AP_ManualCheckHeader, and AP_OpenInvoice tables to see what the system was entering for me.
I dumped the resulting data to a text file and included field names. I then opened the text file in Excel and deleted all blank columns and defaults related to the vendor. (Note, I had to go back into the file with a text editor after saving the file to correct text values that had leading zeros.)
I then deleted the manual check reversal I had manually entered and created a VI Import job using the above text file as a source. The import worked. I then slowly removed columns to determine 1) the minimum column list needed to get the import to work, and 2) what column I was missing that caused my ""out of balance"" error.
#2 first. I had assumed that if I provided the invoice number, the invoice amount paid would automatically populate, just like it does when entering by hand. WRONG (that ASS-U-ME thing bit me again!) You must enter the amount of the invoice being reinstated as a negative number. Otherwise the system brings in a 0. The resulting error from the VI job is the same you get entering the reversal by hand and changing the invoice amount to $0. The invoice distribution does not equal the amount of the check. Therefore it is out of balance.
#1 - The list of columns I had to populate to get the import to work correctly:
H.BankCode
H.CheckType ('R')
H.CheckNo
H.APDivision
H.VendorNo
H.CheckAmt
L.InvoiceNo
L.InvoiceAmt
I thought I would share this for the next poor soul who comes along trying to reverse a batch of checks.